The story told by the man at the center of the most striking allegations in the Penn State sex-abuse scandal is expected to take center stage Friday, as two former university administrators face preliminary hearings on perjury charges.

But it remains an open question whether assistant football coach Mike McQueary will be called to retell his tale during proceedings against suspended athletic director Tim Curley and retired university vice president Gary Schultz.

"In order to prove perjury, we're going to have to prove that the defendants made a material statement under oath, and two other witnesses have evidence contrary to what that statement was," said Senior Deputy Attorney General E. Marc Costanzo.

Costanzo would not say whether prosecutors plan to call on McQueary to help fulfill that burden Friday - a hesitancy veteran defense attorneys said could indicate concern over the increasing scrutiny of the coach's story.

A grand jury concluded last month that Curley and Schultz, who oversaw the university police, failed to notify authorities when McQueary allegedly told them in 2002 that he had seen former defensive coordinator Jerry Sandusky raping a boy in the locker room showers.

Both men later lied under oath about their knowledge of the incident, the panel said. Curley and Schultz have denied the allegation.

"Mr. Curley and Mr. Schultz look forward to the preliminary hearing to start the process of clearing their good names and demonstrating that they testified truthfully to the grand jury," their attorneys, Caroline Roberto and Tom Farrell, said in a statement this week.

Unlike Sandusky, who faces 50 counts of sexual abuse involving 10 victims, the charges against Curley and Schultz hinge solely on what McQueary did or did not say during that 2002 meeting and what the administrators did or failed to do about it.

The preliminary hearing is to take place in Harrisburg before Dauphin County Court Judge William C. Wenner.

On Tuesday, Sandusky waived his own preliminary hearing, at which McQueary was scheduled to testify.

According to the grand jury's 23-page report, McQueary told the panel that he saw Sandusky sodomizing a child whom he believed to be a 10-year-old boy in the showers of a campus gym, the grand jury said.

McQueary, then a 28-year-old graduate assistant, said he reported the incident to head football coach Joe Paterno, who in turn notified Curley and Schultz. A week and a half later, McQueary retold the story again to all three men, but they never told police, the grand jury said.

The university fired Paterno on Nov. 9 for failing to do more, though prosecutors have said he fulfilled his legal responsibility by notifying his superiors.

Paterno, Curley, and Schultz have all maintained that they did not recall McQueary being so explicit in his recollection.

Curley and Schultz told the grand jury that McQueary described seeing "inappropriate conduct" that made him uncomfortable but never detailed any specific sexual misconduct.

Sandusky has contended that nothing sexual occurred. In an interview with NBC News last month, Sandusky conceded he often showered with young boys but maintained he was merely "horsing around" the day McQueary purportedly walked in on him.

On Wednesday, one of Sandusky's attorneys, Karl Rominger, suggested that his client may have been teaching the boy how to shower.

"There are a lot of juvenile delinquents . . . who have to be taught basic life skills like how to put soap on their body," he told Harrisburg television station WHTM.

Questions about McQueary's credibility have been raised in recent weeks.

In the days after Sandusky's arrest and under intense public criticism for failing to stop the purported rape, McQueary sent an e-mail to a friend stating he had intervened and reported the incident to authorities. State College and university police have since said they have no record of such a report.

On Sunday, the Harrisburg Patriot-News reported that a McQueary family friend testified before the grand jury that the coach specifically told him three times that he had not actually seen any sexual activity involving Sandusky

"If this information is true, and we believe it is, it would be powerful, exculpatory evidence and the charges against our clients should be dismissed," Curley's and Schultz's attorneys said.

But Friday's preliminary hearing is not likely to provide many opportunities for them to challenge McQueary's story even if he is called to the stand.

State prosecutors must only convince a judge that there is enough evidence to allow their case to proceed to trial - a relatively low burden.

Defense lawyers will have the opportunity to cross-examine any witnesses called by the state, but questions of credibility are typically barred from such early proceedings.

Contact staff writer Jeremy Roebuck at 267-564-5218, jroebuck@phillynews.com, or @inqmontco on Twitter.